Hmm, I can beat Rock N' Roll racing on the hardest difficulty pretty quickly. I've beaten that game about 8 times now. I know exactly what to do, what upgrades to buy, when to start saving money.
I've actually thought about writing an FAQ on the game, most I've seen are pretty poor quality and don't explain enough info.
You can't really beat the game fast though, since you have to go through all the races.
I really don't go for speed records in games much, and I don't replay games too much either...
I can beat Link's Awakening for the Gameboy pretty fast. And In Mario's Picross I have some pretty high scores in the time trials... man how I love that game.